The present invention regards to spot welding heads of the type comprising:
a pair of electrodes supported by respective supporting bodies and movable with respect to each other between an open position and a closed position,
an actuator device to control the movement of the electrodes between the open position and the closed position,
electric conductors connecting the two electrodes to the terminals of a transformer which is located at a remote position with respect to the welding head, and
a tubular sheath portion, into which at least part of at least one of the aforesaid electrical conductors is guided, having a loop portion with ends rigidly connected to the rear ends of the two supporting bodies of the electrodes.